Hi, On 11/20/2013 03:45 PM, Matthew Gretton-Dann wrote: > On 20 November 2013 17:57, Christopher Covington <c...@codeaurora.org> wrote: >> Hi, >> >> We've noticed an issue trying to use the Linaro AArch64 binary bare metal >> toolchain release with the MMU turned off for some low-level tests. >> >> Anytime puts, sprintf, etc. gets called, a reent structure gets created with >> references to STDIN, STDOUT, STDERR FILE types. A member in the __sFile >> struct, _mbstate, is an 8 byte struct, but is not aligned on an 8 byte >> boundary. This means that when memset (or a similar function) gets called on >> this struct, and doesn't operate one byte at a time, a data alignment fault >> will be generated when operating out of device memory, such as on a system >> where the MMU has not yet been turned on yet.
We believe to have narrowed down the issue to the AArch64 optimized memcpy/memset implementations that assume unaligned accesses will not fault. While the current AArch64 libgloss startup code turns the MMU on so such accesses will succeed, I don't think turning on the MMU should be required of all startup code. Would it be possible to modify these routines to make only size-aligned accesses without degrading performance? If a single implementation can't make everyone happy, should the ifdefs around them perhaps be expanded to include something about requiring the MMU to be on? Thanks, Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation. _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
